(374r) Synthesis and Characterization of Multi-Ionic Block Copolymers for Chemical and Biological Protective Clothing Applications

Geopolitical instabilities in the world have created increased awareness of potential chemical and biological threats. One proactive approach to this situation has been the development of multi-ionic block copolymers as selective materials for chemical and biological protective clothing (CBPC) applications. This study discusses the synthesis of sulfonated amine block copolymers and the effect of multiple ionic domains on the morphology and transport properties of polymeric membranes for chemical protective clothing applications. The monomers 2-(tert-Butylamino) ethyl methacrylate (TBAM), 2-ethoxy ethyl methacrylate (EEM), and styrene were used to prepare the block copolymers by atom transfer radical polymerization (ATRP). The copolymers were then sulfonated by chemical grafting with pendants of sulfobutyl groups onto the polymer structure. Properties of the resulting membranes were determined as a function of block composition and incorporation of sulfonic groups, using a series of materials characterization techniques (e.g., FT-IR, TGA, AFM, SAXS). The results indicate that the ion exchange capacity and water absorption of the membranes had a similar pattern after the incorporation of each block in the structure, where the increase of these properties were proportional to the amine block composition. In addition, the results show that the interaction between multi-ionic domains improves the thermal stability of the polymeric structure. This interaction also caused morphological changes, which affected the transport properties of the membranes and their performance for use in CBPC applications. For example, selectivities of up-to-three orders of magnitude for a simulant of Agent Sarin has been obtained, while maintaining low breathability (water vapor transport rate < 1500 gm² day^-1).